Method and apparatus for capping, individually or in groups, container cans for food products and drinks, and cans or groups of cans capped in this manner.
1. Technical Field
The present invention is directed to the hygienic protection of container cans for food products and drinks, and in particular drink cans having in their upper end a tear-off opening through which the drink is consumed, possibly by bringing the can direct to the mouth.
2. Background Art
The widespread practices of conserving drinks in cans has raised the general problem of safeguarding the health of the user. In this respect, after being filled, the cans are transported and stored without it in practice being possible to protect them from dust or other more dangerous contaminants, making the consumption of the liquid highly anti-hygienic whether the liquid is poured into a tumbler, or, much more serious, whether the user drinks it directly from the can.
The situation is further aggravated by the appearance of cans in which the opening tab is not pulled off, but instead bent down into the interior of the can, into direct contact with its contents.
The U.S. Pat. No. 5,088,269 discloses a method and an apparatus in which a film of thermoformable plastic material is applied to the tops of a plurality of cans.
The portions of the film overlying the top of the cans are softened by heating limited to the areas in alignment with the tops of the cans but smaller than the can tops.
The unsoftened areas of the film surrounding the softened areas are pushed in direction of the tops of the can and snap beneath the rim of the can lops, providing a cover which does not mate with the upper surface, or lid, of the can but is stretched at a distance therefrom resting on the rim.
The areas of the film distant from the lid are exposed to breakage while the cans are transported and stored, and the air contained in the sealed chamber under the film is subjected to condense and gives rise to highly anti-hygienic mildew.
The method and the apparatus of U.S. Pat. No. 5,008,269 do not fully satisfy the requirement of avoiding contamination.
There is therefore the need to protect the can upper end containing the opening tab from dust and other contaminants
Accordingly, an object of the present invention is to rationally satisfy the aforesaid requirement without substantially affecting the calming cost.
A further object of the present invention is to provide packaging means for at least two cans arranged to provide packs of at least two cans held together by a single support sheet, while at the same time protecting their lids from contamination.
The present invention is based on the solution of directly forming on the upper portion of the can, by basically using this as a forming die, a cap of food-quality plastic material which xe2x80x9chermeticallyxe2x80x9d covers this upper portion.
The method of the present invention comprises heating a film of thermoformable plastic material and positioning it on the upper portion of the can, then making it adhere to the surface of said upper portion by exacting the air contained between this surface and the film. Finally, the film portion adhering to the can upper portion is separated from the rest of the film. During the described procedure, the film is heated to a suitable temperature such that the film is able to satisfy the conditions for thermoformability, after which, by hardening following cooling, it adheres intimately to the surface which it covers, and retains its shape.
A cap is obtained and formed from a film portion which mates with and covers the surface of the upper portion of the can.
This cap, which can be easily and rapidly removed by the consumer, covers, and effectively and hermetically protects, from dust and any other contaminant, the region comprising the can opening and the entire can upper part and upper edge contacted by the lips, thereby maintaining this region in a positively hygienic condition.
Moreover, after the can has opened, the same cap can be further used to close the can and hence prevent accidental contamination by foreign bodies. The cap forming procedure is very rapid and does not retard the production rate of the canning line in which it is inserted.
Moreover the apparatus required for effecting the procedure is relatively very simple and of low cost.